Return to the Organic Rose Growing Forum
| Post a Follow-Up
Severe Powdery Mildew
| | |
Posted by amyjean 5a (My Page) on Thu, Jul 17, 08 at 15:09
| I have inherited a garden filled with roses, many I believe are hybrid teas, which always seem to be aflicted with something. Many, many are, I think, an old garden rose. I'm not sure, but they seem to bloom only once and are quite fragrant. Unfortunately, all of these roses seem to be diseased. I'm thinking of tossing the hybrid teas, but the OGR's are so wonderful! That is, except for an extremely thick layer of powdery mildew all over them and a little of what appears to be anthracnose.
My question is this: It seems that the recommendation for powdery mildew and the anthracnose is to remove the affected part of the plant and then use fungicide on the rest. This would mean removing almost the entire plants! I'm on round 2 this week of using Planet Naturals "Safer" garden fungicide, but this doesn't appear to have had any effect. If anything, the plants are worse. Is there a way to save this garden? I'm beginning to feel a little overwhelmed. Any help is appreciated. Thank you, Amy |
Follow-Up Postings:
RE: Severe Powdery Mildew
| | |
Two things I use to keep Powdery Mildew off the plants that are susceptible are 1) mix 1 teaspoon baking soda in 1 quart of water, or 2) make a 50/50 mix of fat free milk and watrer. These are both sprayed every 5 days to control PM on plants already covered or every 7 to 10 days to prevent PM from getting started.
Dig in the soil and see what you have because a good, healthy soil will aid greatly in growing strong, healthy plants that can better ward off plant diseases and pests. |
RE: Severe Powdery Mildew
| | |
| I'm getting some decent results fighting PM with apple cider vinegar spray. Three TB vinegar to five liters of water. A quick spray on susceptible plants every three to five days, depending on weather, seems to be working. |
RE: Severe Powdery Mildew
| | |
| First I've heard of using an acidic substance to control Powdery Mildew which seems to grow better on acidic leaf surfaces. The baking soda and milk work at controlling PM because they change the pH of the leaf surface to alkaline which makes an environment the PM cannot live on. Be interesting to know if others have similar results with vinegars, which usually kill plant leaves. |
RE: Severe Powdery Mildew
| | |
| My gosh, what great information. I'm a new rose grower. Just sticking whatever I can find into the ground and watching it grow. I purchased two Showbiz the other day from Lowes (coldn't pass up $7.50/per). I am not familiar with powdery mildew but I think they have it (know all too well about blackspot though). I'll give the baking soda and or milk mixed with water a try and see if it has an effect on these wonderful roses. Thanks! |
RE: Severe Powdery Mildew
| | |
| Hi Kimmsr. I started with the apple cider vinegar solution after seeing it here on gardenweb, mainly because I happened to have a quart bottle of it! My PM problem is not extensive--only four to five shrubs affected and only one of these with PM on every leaf. My Mm Isaac Pereire gets curled leaves and puny blooms. The vinegar solution definately arrests the progress--the day after a spray it is pretty much gone. My guess is that the specific ph that PM needs can be altered either way--with an acid or a base. Now I'm trying the Cornell Formula on some roses and the vinegar solution on others (trying to find roses equally affected). I'm getting obsessed! A question: Does it completely nullify your efforts when you spray in the evening and it rains the next day? |
RE: Severe Powdery Mildew
| | |
| I'm experimenting next with the milk and water. Will compare the three: the Cornell, the vinegar water and the milk water. Does the milk water make your garden smell at all bad? |
RE: Severe Powdery Mildew
| | |
| Thank you everyone for responding to my question! KIMMSR, I was under the impression that the theory behind the milk (I thought I read this somewhere?) was that it contained "healthy" bacteria or other organism that would inhibit the powdery mildew. Toward that end, I thought that raw milk must work versus pasteurized, but perhaps it's only ph? No one seems to ever mention raw milk, so perhaps ph is the only mechanism. Any thoughts? Again, thank you everyone for the help. Amy |
RE: Severe Powdery Mildew
| | |
| The original research on milk did use raw, whole, milk, but very few of us, in the USA, have access to raw milk unless we have our own source, hence the use of the fat free milk because some researh indicates that the pasturaization process changes the fat globules in the milk and they apparently do harm to plants. Pasturized milk will not have many, if any, bacteria healthy or not since the temperature is meant to kill those wee critters adn the good bacteria or easier to kill off than the disease pathogens would be. |
RE: Severe Powdery Mildew
| | |
| Here's a crazy idea. What about using yoghurt instead of milk? It's full of good bacteria. Of course, the sour taste must mean it's acidic--but maybe that would still alter the ph, though in the other direction, and disturb the necessary enviornment for fungus... What do you think? (I have definately had some good results with vinegar water and PM) |
RE: Severe Powdery Mildew
| | |
| I've not found anyone, yet, that has tried Yogurt for anything other than eating, although I have seen Pasturized Yogurt out there now. |
|
|
|
|
